1. Field of the Invention
The invention relates generally to improved apparatus and methods for reprocessing items with lumens, and, more particularly, to apparatus and methods that involve flowing a liquid through a divided chamber containing the item to be cleaned and sterilized.
2. Description of the Related Art
The reprocessing (i.e., cleaning and decontamination) of items that come into contact with the bodily substances of people or animals such that they are substantially “substance free” (of, e.g., viruses, bacteria, detergent, sterilant, lipids, etc.) represent an immense and ongoing challenge. This challenge has been underscored by a recent article entitled “Widely used sterilizer under attack” (published in Jan. 21, 2003 edition of the newspaper USA Today). The article describes a fatal outbreak of bacterial infection that was linked to the improper sterilization of hospital bronchoscopes. Despite the hospital's use of one of the most popular sterilizing systems, tests performed by the Centers for Disease Control and Prevention found bacteria on the system's water filters and in its rinse water. This and other infection outbreaks have led to continuing controversy over how best to clean and sterilize used endoscopes. These challenges persist to the present day.
The contaminants typically found on tubular or “lumened” medical items, such as endoscopes, are especially difficult to remove. In addition to fecal mater, loose cellular debris, blood and blood products, viruses, and bacteria, an endoscope can be coated with various hydrophobic films, such as “biofilm” material. A biofilm typically comprises cells, both dead and alive, cell debris and extracellular polymer substances. Once biofilm is formed by microorganisms (including bacteria, fungi, and protozoans), these microorganisms can colonize and replicate on the interior surfaces of tubing, forming a protective slime layer known as a “glycocalyx” that is especially difficult to remove.
Merely soaking endoscopes in a sterilant or detergent is unacceptable since numerous pockets exist within the tubing where the sterilant or detergent cannot reach effectively, which leaves areas of contamination within the endoscope. Moreover, with the prevalence of highly contagious diseases such as hepatitis B and C and Acquired Immune Deficiency Syndrome, as well as the pathogens MRSA (Methicillin-resistant Staphylococcus aureus) and Clostridium difficile, reliable sterilization or disposal of all used medical tools seemingly becomes mandatory. Yet, while many medical instruments today are routinely cleaned, disinfected, and reused, experts in the field recently have warned that some of the more difficult to clean and sterilize medical items are putting people at risk. For example, the website “myendosite.com” contains scores of recent references involving infection and endoscopy in the news (see myendosite.com/infection_control_media.htm).
Many attempts to improve sterilization apparatus and methods have been tried over the years. For example, a variety of gas sterilization methods has been investigated in the past. Methods using ethylene oxide and other disinfecting gases are widely used for sterilizing a wide range of items, from contact lenses to surgical instruments.
A sterilizing method must effectively kill all organisms, including spores, without damage to the article or goods being sterilized. Moreover, before sterilization can take place, the instrument must be cleaned to the FDA quantifiable validated standard of clean. Indeed, no reprocessor on the market can perform this other than the unique “push/pull reprocessors” created by the inventor and described below.
So-called “push/pull reprocessing systems” are automatic apparatuses that include a chamber containing a baffle with one or more openings through which water (or another fluid) surges in a synchronous fashion back-and-forth (hence “push/pull”) through the opening or openings in the baffle. When soiled items, such as endoscopes and other lumened instruments, are placed within an opening in the baffle, fluid also surges upon and through them. Accordingly, a back-and-forth “scrubbing action” is created by the surging fluid the contacts any accessible surface on an item, including any lumen or lumens.
For example, U.S. Pat. No. 5,711,921 by Langford discloses a medical apparatus cleaning mechanism that includes a container having a first chamber and a second chamber, with the container adapted to accept a medical instrument such that a first portion of the medical instrument lies in the first chamber and a second portion of the medical instrument lies in the second chamber. Pumping means then simultaneously increase fluid pressure within the first chamber of the container while decreasing fluid pressure within the second chamber until the cycle is reversed, i.e., the fluid pressure in the second chamber increases while the fluid pressure in the first chamber synchronously is decreased.
While the Langford apparatus is known to provide superb cleaning and sterilization, the teachings of the Langford patent appear limited to the use of the apparatus with a single-size lumen diameter and do not specify how to evacuate the entire lumen volume per each change in fluid flow direction (i.e., a “stroke”).
U.S. Pat. No. 6,534,002 by Lin further notes alleged shortcomings of the teachings in Langford as follows: “One significant problem with this surging mechanism for cleaning endoscopes results from the fact that endoscope channels often have different diameters at their opposite ends. As fluid flows from the larger-caliber end of an endoscope channel to the smaller-caliber end, particulate matter and human tissue, secretions, and excrement can become lodged in the smaller-caliber end and extremely difficult to extract. Another problem with the surging mechanism results from the frequent change in directional flow of fluid through the channels of an endoscope. In cleaning an endoscope, debris must travel a long distance, sometimes more than 150 cm, to traverse the length of the endoscope before the debris can exit the endoscope. In surging methods of cleaning endoscopes, some fluid, debris, and air pockets may move back and forth within the endoscope channel, but never travel far enough to exit the channel before the next directional shift in flow occurs. Thus, some debris and air pockets can remain trapped in the central portion of an endoscope channel with the surging method of cleaning.”
The main thrust of how the Lin patent proposes to deal with these shortcomings involves generating a flow of sanitizing solution through a lumened instrument in predominantly one direction, from the smaller-caliber end to the larger-caliber end, to clean or sterilize the inner surface of the device.
However, flowing a fluid in “predominantly one direction” does not necessarily result in better cleaning or sterilizing action; indeed, material may become trapped in complex lumened instruments (such as a restrictor valve in a colonoscope or the spring and guide wire of a biopsy forceps) if a recurring back-and-forth motion is not used to dislodge it.
From the above, it can readily be seen that complex lumened medical devices present unique challenges. Some instruments (e.g., a bronchoscope) have a main lumen of one diameter and another lumen of smaller diameter branching off the main lumen, presenting two resistance ratings inside the same instrument. Furthermore, various lumened instruments have restrictor valves inside the lumen narrowing the fluid path in one direction. This acts as a point of blockage or increased resistance if debris is pushed up against the restrictor. Thus, for those devices that have different size internal lumens in the same instrument, as well as for those that can be 6 feet or longer in length (e.g., a colonoscope), resistance to fluid flow during cleaning and sterilization presents a difficult problem.
Accordingly, it would be desirable to provide an apparatus and method that carry out effective cleaning and sterilization of even complex lumened instruments quickly and thoroughly, while reducing undesirable effects. In addition, it is desirous that the fluid flow about the exterior of a lumened instrument cause sufficient turbulence to clean the outside of the instrument as well.